What you actually need to build a working computer

A functioning PC requires seven essential parts: a motherboard, a CPU (processor), RAM (memory), a storage drive, a power supply, a case, and a graphics card (or integrated graphics if your CPU has them). Without any one of these, your computer will not turn on or will not display anything on screen. Everything else—extra fans, RGB lighting, wireless cards—is optional.

The good news: these parts work together in a straightforward way. The motherboard is the foundation that everything plugs into. The CPU does the thinking, RAM holds temporary information while the computer is running, the storage drive holds everything permanently, the power supply sends electricity to all the parts, the case holds it all together, and the graphics card (or your CPU's built-in graphics) sends an image to your monitor.

Key Takeaways

  • A PC needs exactly seven core parts to function: motherboard, CPU, RAM, storage drive, power supply, case, and graphics card or integrated graphics.
  • The motherboard determines which CPU, RAM type, and graphics card will physically fit, so choose it first or verify compatibility before buying other parts.
  • A CPU with integrated graphics can display video without a separate graphics card, saving money if you are not gaming or doing graphics-heavy work.
  • Storage drives come in two types—SSDs (faster, more common now) and HDDs (slower, cheaper for large amounts of data)—and you can use both at once.
  • The power supply wattage must match your parts' total power draw, and buying 20 to 30 percent more capacity than you need prevents strain and extends its lifespan.

The motherboard: your starting point

Choose your motherboard first, because it determines what everything else can be. The motherboard has a socket—a physical slot—that accepts only certain CPUs. It also has slots for RAM, a slot for a graphics card, and connectors for your storage drives and power supply.

Motherboards are named by their socket type. Common ones right now are Intel LGA1700 (for current Intel CPUs), AMD AM5 (for current AMD CPUs), and older sockets like Intel LGA1200 or AMD AM4 if you are buying used or budget parts. When you pick a motherboard, you have already decided whether you are building an Intel or AMD system.

Motherboards also come in different sizes: ATX (full-size, most common), Micro-ATX (smaller), and Mini-ITX (very small, for compact cases). Your case must fit your motherboard size, so check that before you buy.

The CPU: the processor that does the work

The CPU (central processing unit) is the brain of your computer. It runs all your programs and games. CPUs from Intel and AMD are not interchangeable—an Intel CPU will not fit in an AMD motherboard socket, and vice versa.

Many modern CPUs come with integrated graphics, meaning they can display video to a monitor without a separate graphics card. Intel calls theirs Iris Xe or UHD Graphics; AMD calls theirs Radeon. If you are doing everyday work, watching video, or light gaming, integrated graphics are often enough. If you are playing new games at high settings or doing video editing or 3D rendering, you will need a dedicated graphics card.

The CPU plugs directly into the motherboard socket and is held down by a lever. It is one of the few parts that can be damaged by static electricity, so touch a metal part of your case before handling it.

RAM: temporary memory while your computer runs

RAM (random-access memory) is temporary storage that your computer uses while it is running. When you turn off the computer, everything in RAM disappears. RAM speed and capacity matter: most new builds use 16 GB as a baseline, though 8 GB works for basic tasks and 32 GB helps if you are editing video or running many programs at once.

RAM comes in different types that match your motherboard: DDR4 or DDR5 are current standards, though older boards use DDR3. Your motherboard manual will tell you which type it accepts. RAM sticks plug into vertical slots next to the CPU, and they only fit one way—the notch in the stick lines up with a key in the slot.

Most motherboards have two or four RAM slots. You can start with one stick and add more later if you need it, as long as you buy the same type and speed.

Storage drives: where your files live permanently

A storage drive holds your operating system, programs, and files permanently. You need at least one. There are two types: SSDs (solid-state drives) and HDDs (hard disk drives).

SSDs are faster, more reliable, and have no moving parts. They are the standard choice now. A 500 GB SSD is enough for Windows and a few programs, but 1 TB is more comfortable. SSDs plug into an M.2 slot on the motherboard (the most common type now) or a 2.5-inch SATA slot (older style).

HDDs are slower but much cheaper per gigabyte, so they are useful if you need lots of storage for video files, photos, or backups. You can use both an SSD and an HDD in the same computer—put Windows and your programs on the SSD for speed, and use the HDD for large files.

The power supply: electricity for all your parts

The power supply converts wall electricity into the right voltage for your computer parts and distributes it through cables. You need one that provides enough wattage for your CPU, graphics card, and other parts combined, plus a safety margin.

To estimate wattage, add up the power draw of your CPU and graphics card (both listed on their spec sheets), then add 100 to 150 watts for everything else. If your total is 400 watts, buy a 500 to 550-watt power supply. Running a power supply at 80 percent of its rated capacity or less extends its lifespan and keeps it cooler.

Power supplies have a 24-pin connector for the motherboard, an 8-pin or 4-pin connector for the CPU, and various connectors for graphics cards and storage drives. Your motherboard manual shows where each one plugs in. Buy a power supply from a reputable brand—Corsair, Seasonic, EVGA, and Thermaltake are common—because a cheap one can damage your parts or fail suddenly.

The case: the box that holds everything

The case is the metal box that holds your motherboard, power supply, and drives. It also provides airflow to keep your parts cool. Cases come in different sizes to match different motherboard sizes: ATX cases fit ATX motherboards, Micro-ATX cases fit smaller boards, and so on.

Cases also vary in how many fans they come with and how much space they have for cooling. A case with at least two fans (one pulling air in, one pushing air out) is a good baseline. If you are buying a high-end graphics card or CPU that runs hot, look for a case with more fan space or better airflow design.

When you buy a case, check that your power supply will fit (some cases have size limits) and that your motherboard size matches. The case manual or product page will list these specs.

The graphics card: optional if your CPU has integrated graphics

A graphics card (also called a GPU) processes images and video. If your CPU has integrated graphics, you do not need a separate card for everyday use. But if you are gaming, editing video, or doing 3D work, a dedicated graphics card will be much faster.

Graphics cards plug into a long slot on the motherboard called a PCIe slot. Most modern cards use PCIe 4.0 or 5.0, and they are backward-compatible with older slots, though they will run slower in older motherboards. Graphics cards also draw significant power, so they plug into the power supply with 6-pin or 8-pin connectors.

Graphics cards from NVIDIA and AMD are the main options. NVIDIA cards are called GeForce, and AMD cards are called Radeon. Your choice depends on your budget and what you are doing—both work well for gaming, but some software favors one brand or the other.

Frequently Asked Questions

Can I build a PC without a graphics card?

Yes, if your CPU has integrated graphics. Intel and AMD both make processors with built-in graphics that can display video to a monitor. You will not be able to play new games at high settings, but everyday computing, web browsing, and video watching work fine. You can always add a graphics card later if you need it.

How do I know if parts are compatible before I buy them?

Start with your motherboard choice, then check the manual or product page for the CPU socket, RAM type, and PCIe slot version it supports. Cross-reference each part you want to buy against those specs. Websites like PCPartPicker let you select parts and flag incompatibilities automatically, though you should still verify the motherboard manual yourself.

What if I do not know how much power my parts need?

Look up the power draw (usually listed as TDP or watts) for your CPU and graphics card on their spec sheets, add them together, then add 100 to 150 watts for the rest of the system. If you are unsure, a 650-watt power supply works for most mid-range builds. Buying more capacity than you need is safer than buying too little.

Do I need extra cooling fans beyond what comes in the case?

Most cases come with one or two fans, which is enough for a basic build. If you are using a high-end CPU or graphics card that runs hot, or if your case is small with limited airflow, adding one or two more fans helps keep temperatures down. You can test temperatures after building and add fans later if needed.

Can I upgrade parts later, or do I need to buy everything at once?

You can upgrade most parts later—RAM, storage drives, and graphics cards are straightforward to swap out. The motherboard, CPU, and power supply are harder to change without rebuilding much of the system, so think carefully about those choices upfront. Everything else can wait until you have the budget or feel the need for more performance.